Insulating cap for pigtail connectors



Feb. 1, 1955 c. A. BADEAU INSULATING CAP FOR PIGTAIL CONNECTORS INVENTOR. A. 5405/1 Filed Aug. 8, 1951 ATme/VB United States Patent 2,701,273 INSULATING CAP roR .PIGTAIL CONNECTORS Carroll A. Badeau, Westflel'd, N. J., assignor to The Thomas & Betts Co., Elizabeth, N. J., a corporation of New Jersey Application August's, 1951, Serial No. 240,837

3 Claims. (Cl. l7-4'138) The invention relates to an insulating cap for pigtail connectors for use in those situations where the ends of conductors are grouped together to form a splice and the splice secured within a metal sleeve functioning as a connector, and the metal connector then contained within :a shielding cap of insulating material.

The invention is disclosed in connection with a cap formed of some rubber-like resilient material and which is provided internally with a seat in the form of an integral :fia-nge operative to resist the accidental escape of the connector from the cap.

Unless extreme care .is exercised in maintaining the assembly of pigtail splice,;connector and insulating cap as intended the-connector is apt to lose its cap and thus become exposed for accidental short-circuiting of the associated-electrical system. For instance, assume that the connected splices are in position in a "junction or outlet box and with the cap of each splice more or less -,held in ,placethereon, and that an electrician desires to branch a circuit conductor from such a box. He often *drills a hole through an adjacent building framework through which to trail the conductor and it the framework interferes with the desired ,path of the condoctor he ;is apt to tug or pull on that part .of the conductorwhich is externally of the box in order to have the conductor involved in the intended installation lie more to his liking. If the cap of the associated assembly is held in the box in any way and there is -a pull on any one of the associated conductors and thus on the connector to which the conductors are secured, it follows that the connector is pulled away from its shielding cap and 'thus the connector and with .it the associated -conductors'are exposed for a possible short-circuiting of the related system.

:An object of the invention .is to provide a form of cap which in addition to its insulating functions will absorb, cushion and thus resist any loads applied to the conductors in a directiontoseparate the connector and its cap. Broadly, I attain this objective by making the cap resilient in the portion thereof between the :flange and itsopen end and in making this portion in the form of .a normally rigid, but spring-like, column, but which column has anarea of reduced cross section of material capable of collapsing inwards under axially directed load and which cap when released of any such distorting load will act by virtue of its own resiliency to restore itself, the connector and the conductors carried thereby to their initial positions.

Various other objects and advantages 0f the invention willbe in par-tobvious vfrom -an'inspection of the accompartying drawings and in ,part will he more vfully set :forth in the following description of one form of insulating cap embodying the invention, and the invention also consists in certain new and novel features of construction and combination of ,parts hereinafter set forth and claimed.

In the drawing:

Fig. ii :is 'a view in .axial section of an insulating cap for pigtail connectors .forming a preferred embodiment of the invention;

Fig. 2 is a transverse sectional view taken on the line 2"2 of Fig. .1, looking upwardly in the direction indicated by the arrows;

Fig. 3 is a view of the assembly of cap of Figs. 1 and 2 and connector therein in their unloaded normal operative position; and

2,701,273 Patented Feb. 1, 1955 Fig. 4 is a view of the assembly of cap and connector with the wall of the cap collapsed in the portion thereof between the base of the cap and the flange by reason of a squeezing pressure axially directed, incidental to a downward pull on the conductors.

In the drawings there is disclosed a plurality of insulated conductors 10 having bare ends assembly in parallel or twisted relation to form a splice. The splice is permanently secured in a connector 11 inturn housed within an insulating cap 12 particularly forming the subject-matter of this disclosure. The connector 11 is a thin-walled, sheet metal, cap-like stamping and for the most part is of cylindrical form. The lower open end of the connector is flared outwardly to form an annular rim 13 forming a flat base fashioned for continuously engaging its seat as hereinafter described. The bare ends of the conductors are secured within the connector by crimping as evidenced by the indentation 14 in the cylindrical side of the connector, and inthis respect the splice and its connector resemble conventional forms of similar devices.

The cap 12 is molded from a rubber-like material having some elasticity and in the device illustrated is molded from a 'Vinylite thermoplastic material having plastic memory and having sufficient elasticity to revert autornatically to its molded form when freed frorn'deforming loads thereon. The cap is substantially of cylindrical form with an outlining annularwall 15 with a closed end 16 and its opposite annular base-forming end 17 is wide open. An internal flange '18 projects integrally from the outlining Wall of the Cap about its mid-length and operates to divide the interior of the cap into an upper chamber 19 dimensioned for receiving the upper "portion of the connector 11 with a freely sliding fit therein and to form a lower chamber 20 of :greater diameter than the upper chamber and through which extends the insulated parts of the conductors.

The flange 18 is inclined upwardly at an angle of about 45 degrees in the direction away from the :open .end 17 and .is provided centrally thereof with a circular hole 21 extending t-herethrough and having a-d-iameter greater than thediameter of the upper cylindrical part oft-he connector but less than the diameter of its rim .13.

The outer perimeter of the wall 15 in the lower portion thereof between the open .end 17 and the flange 1-8, and

thus the part encircling the :lower chamber .20 is formed with a shallow annular recess 22. This recess considered in axial section as shown in Figs. 1 and 3 is a long, shallow concave are at its center which merges at its ends into the adjacent sides of the outer wall face through convex curves of relatively short radius to form a compound curve. The recess 22 has the effect of providing the Wall with a weakened annular area 23 having a cross section of material considerably thinner than the section at any other part of the wall.

Differently defined, the cross section of material at the recess .22 is less than the cross section of material above and below the recess and less than the cross section of material .at both the open end 17 and at the thickened portion from which the flange 18 projects. Placing the recess 22 on the outer perimeter of the collapsible column rather than on the inner perimeter is what causes the column to collapse inwardly where there is room rather than outwardly where there is no room because o'f closely positioned similar devices.

,It can be assumed that under normal operative condi tions, that is, without squeeze loads thereon, the instant device functions as do known forms of pigtail .sp'licers when capped by a shield of insulating material. For the purpose of showing the device operative .in its novel aspects it will be assumed that the assembly .is in .a junction or outlet box with a wall thereof :shown 'at A and having an aperture .B through which the conductors 10 extendvas usual. Under these conditions any pull on the conductors will move the cap '12 into engagement with the wall 'as shown in Fig. 3., if not already there. Ordinarily, the electrician will feel the resistance imposed by this contact with the wall and will refrain from exerting any further load on the conductors. However, in the event there is a further pull on the conductors in a tendency to squeeze the portion of the wall between its open end base 17 and the flange 18, the load imposed by any such pull will produce several results in succession. First, the inner perimeter 24 of the flange will give somewhat downwardly, that is, axially towards the open end to increase slightly the initial angle as shown in Fig. 1, and will also move inwardly, thus reducing the normal diameter of the hole 21, thus further tending, in addition to the elastic resistance of the flange, to resist the escape of the rim 13 backward, that is, downwardly, through the hole. At this time there will be at least some slight, perhaps trifling, collapsing of the lower portion of the wall in a strictly axial direction so that the wall by virtue of its elasticity will exert a cushioning effect tending to resist any such down pull on the conductors even with the wall in its uncollapsed condition as shown in Fig. 3, and this cushioning effect will ordinarily be suflicient to resist any possibility of the conductors being torn away from the connector.

Then let it be assumed that a more powerful downward pull is exerted on the conductors, a pull sufficient to overcome the normal tendency of the cushioning wall to maintain its initial columnar configuration. Under such squeezing effect a progressively inward collapsing of the wall 15 results and the lower portion of the wall in buckling inwardly eventually assumes the narrow waistlike form at 25 in Fig. 4 with the initially shallow recess assuming the form of a deep annular groove 26 with the immediately adjacent portions of the wall providing overlapping but non-contacting folds 27 and 28. At the rounded bottom 29 of the groove the cross section of the wall becomes much thinner than in the uncollapsed form shown in Figs. 1 and 3. If the pull on the conductor is sufliciently prolonged thereafter the portion of the wall between its open end and the flange approaches or tends to approach a solid column and this resists all deforming loads up to a disrupting mutilation of the assembly.

Differently expressed, the resistance to collapsing of the cap considered as a whole is provided first by the relatively weak resistance provided by the flange 18 and then by the greater resistance provided by the column 15.

In those cases where the wall 15 was made a little thinner than illustrated there was a tendency of the wall to become corrugated in irregular folds as its axial length was decreased. rather than to form the distinct single fold illustrated.

It will be understood that the deformation of the structure when in the collapsed position illustrated has been purposely exag erated to bring out its possible function under abnormally powerful pulls on the conductors, but in ordinary use and with a moderate pull on the conductors the deformation is not so pronounced and in effect almost any deforming of the elastic column will be sufficient to protect the position of conductors in the connector and the connector in the cap.

As the len th of the skirt outlining the lower chamber 20 is desi ned primarily to avoid flash backs it is seen that reducing the cross section of material to provide the weakened area 23 does not interfere with the functioning of the device to defeat flash-backs even when momentarily collapsed as herein noted.

Providing the molded can with the recess 22 herein featured does not add to the expense of manufacturing the cap and does not interfere with the snap-in mounting of the connector.

When released from any squeeze load thereon the cap as a whole, including its internal flange. is returned elastically to its initial molded condition and to its position in the box relative to its wall A and the parts are restored automatically to their normal intended operative condition as shown in Fig. 3.

It is thus seen that the assembly operates as a signal device concealed within the junction or outlet box or otherwise hid from view and is designed to advise the installer when he is exerting too much pull on the conductors. A slight resistance to an initial freedom of draft on the conductors advises the installer that the shield has contacted the wall A or other obstacle in its path with a slight pressure of the rim 13 on the flange as indicated in Fig. 3. The installer will ordinarily pull slightly more on the conductors beyond this point of initial contact to insure a firmer engagement of the connector 11 with the flange 18 and this will perhaps effect some slight resilient bending of the flange, particularly at its inner edge hinging about its entire perimeter. This will cause the flange 18 to become firmly engaged under the rim 13, and thus insure a non-wabbling of the connector on the flange and a centering of the same more or less in the upper chamber 19. Incidentally, this will occur even though the pull on the conductors be at an angle to the axis of the connector, as is quite likely to be the case in actual practice. Beyond this point of traction on the conductors the installer can feel by reason of the more powerful resistance to this pull that the socalled weakened section of the cap wall at the stop wall A has become involved in resisting his pull and, as this collapsed condition of the wall is not a desired condition, he will release his tension on the cables until the abnormal resistance so caused is no longer felt. If the installer should accidentally or otherwise pull on the con ductors to the extent that the column becomes solid, the lack of feeling of resiliency in the'conductors will advise the installer that he has gone too far and that there is then present a possibility of his pulling the conductors away from the connector.

I claim:

1. A one-piece pigtail splicer assembly cap comprising a hollow, thin-wall, molded member formed of an elastic insulating material of substantially cylindrical form,- open at one end and with its side wall provided in spaced relation to said open end with an integral internal flange fashioned to provide a seat for a connector housed within the member and said side wall providing between the flange and its open end an annular column having suflicient rigidity to maintain its configuration when free of deforming forces, the outer perimeter of the column provided in spaced relation to both the open end and to the flange with an outwardly facing annular recess, said column provided at the part thereof having the recess with a reduced cross section of material and said column collapsible into a narrow waist-like form at said recess when subjected to a squeeze pressure between the flange and open end in a direction axially of the column and said column capable by reason of its resiliency of reverting to its initial molded form when released of such squeeze pressure.

2. A one-piece hollow cap for a pigtail splicer, said cap being formed of a resilient material, open at one end and closed at its other end, said cap adjacent its midlength provided with an internal annular flange dividing the interior of the cap into an upper pocket of cylindrical contour in the part thereof adjacent the closed end and a lower pocket of cylindrical contour in the part adjacent the open end, and the outer perimeter of the wall outlining the lower pocket contoured to provide an annular shallow recess with the cross section of material between the annular recess and the inner side of the wall outlining the lower pocket being less than that of the wall in the portion thereof above and below the annular recess, whereby to form the portion of the wall between the flange and the open end as a collapsible column.

3. A one-piece hollow cap for a pigtail splicer, formed of a resilient material, having an open end and provided in spaced relation to the open end in a plane parallel thereto with an internal annular flange, the portion of the cap between, the flange and the open end forming an axially collapsible wall of substantially cylindrical form and said wall provided on its outer side with an annular groove outlining an area of reduced cross section of material.

References Cited in the file of this patent UNITED STATES PATENTS 1,458,247 Schleper June 12, 1923 2,043,499 Vendope June 9, 1936 2,122,252 Hayes June 28, 1938 2,383,018 Shere Aug. 21, 1945 2,468,226 Murphy Apr. 26, 1949 2,560,683 Buchanan July 17, 1951 

